Which of the listed pressure-control valves would be used in a hydraulic system to temporarily divert some, or all of the pump discharge until the additional flow was required?

Correct Answer: Option B — unloading valve

Unloading valves divert pump discharge to the reservoir at near-zero pressure when system demand is met or pressure reaches a set point. This reduces power consumption and heat generation during idle periods, protecting the pump from unnecessary load while maintaining readiness for immediate system activation.